5 8 6 CALENDAR 1920 2-page TLS from Hans Vaihinger. Reports on “Als-Ob” conference. Victor Altmann, of Berlin, member of the Kant Society, is prepared to donate anonymously 5,000 M for a prize on “the relationship between Einstein’s relativity and contemporary philosophy, with special reference to the phi- losophy of Als-Ob.” Asks Einstein to thank Altmann. Pro- poses a three-member panel of judges composed of one “critic” of “your direction,” one “nonpartisan,” and one “friend.” Proposes Moritz Schlick for the latter slot. [23 132]. July 14 TLC to Julio Rey Pastor. Cannot accept any official invita- tion to Spain for the fall because he is exhausted by various obligations. Hopes to pay a visit in the future. [44 766]. 2-page TLS from Edouard Guillaume. Replying to Doc. 71, elaborates on his understanding of the meaning of a clock’s “period.” Claims a confusion exists in relativity theory bet- ween the “period” of a clock and the time measured by it. Encloses a copy of Guillaume 1920a. [11 538.1]. 2-page TLS from Robert W. Pohl. Gives breakdown of requested 8,000 M (see 10 July, in Calendar). GyBP, I. Abt., Rep. 34, Nr. 9, Mappe Pohl. [77 573]. July 15 Submits to the plenary session of the PAW, then temporarily withdraws a paper by a foreign scientist that was meant for publication in the Sitzungsberichte. Is asked to name the topic and author. Kirsten and Treder 1979, p. 239, Nr. 199. ALS from Ernst Cassirer. Offers his study as accommoda- tion when Einstein visits Hamburg to deliver a lecture on the foundations of the theory of relativity. [3 393]. July 16 Completes “To the ‘General Association for Popular Tech- nical Education’” (Vol. 7, Doc. 42). 1-page TLC to Freie Vereinigung für Technische Volksbil- dung. Cannot join the Vereinigung because of heavy com- mitments, but as attachment sends a statement (published as Einstein 1920d) to be used at their discretion. [45 103]. Chairs a session of DPG with Reinhold Fürth and David Reichinstein lecturing. Verhandlungen der Deutschen Phys- ikalischen Gesellschaft 1(1920): 82. July 17 Presents lecture “Grundlagen der Relativitätstheorie” under the auspices of the mathematical-physical faculty of the